KR20190037137A - Adhesive composition and surface-protective film - Google Patents

Abstract

The present invention provides an adhesive composition which has excellent adhesion balance in low and high peeling speeds and has antifouling properties and excellent adhesive performance, and a surface protective film which is capable of forming an adhesive layer from the same adhesive composition, wherein the adhesive layer can be used with respect to a surface base material formed of TAC, PMMA or PET and has excellent antistatic performance without being deteriorated with the passage of time. The adhesive composition of the present invention comprises: a first acrylic polymer of a copolymer which does not contain a polyalkylene glycol ring-containing mono (meth)acrylic acid ester monomer and has an acid value of 0.1 to 1.0 obtained by copolymerization; a second acrylic polymer of a copolymer which is obtained by copolymerizing the polyalkylene glycol ring-containing mono (meth)acrylic acid ester monomer; (D) a trifunctional or higher isocyanate compound; (G) an ionic compound having anions in which the number of fluorine atoms is F7 or more and having a melting point of 25 to 50°C; (E) a crosslinking retardant; and (F) a crosslinking catalyst other than a tin compound as the crosslinking catalyst.

Description

ADHESIVE COMPOSITION AND SURFACE-PROTECTIVE FILM < RTI ID = 0.0 >

The present invention relates to a pressure-sensitive adhesive composition and a surface protective film containing an antistatic agent. More particularly, the present invention relates to a pressure-sensitive adhesive composition containing an antistatic agent, which forms a pressure-sensitive adhesive layer of a surface protective film used for protecting the surface of a polarizing plate by adhering to a polarizing plate constituting a liquid crystal display, and a surface- will be. The pressure-sensitive adhesive composition of the present invention has excellent adhesion performance and excellent antistatic performance without deterioration over time.

BACKGROUND ART [0002] Conventionally, in a process of manufacturing an optical member such as a polarizing plate, which constitutes a liquid crystal display, a surface protective film is adhered for temporary protection of the surface of an optical member. Such a surface protective film is used only for the process of manufacturing the optical member, and is peeled off from the optical member at the time when the optical member is included in the liquid crystal display. Since the surface protective film for protecting the surface of such an optical member is used only in the manufacturing process, it is also generally referred to as a process film.

As described above, the surface protective film used in the process of manufacturing the optical member has a configuration in which a pressure-sensitive adhesive layer is formed on one side of a polyethylene terephthalate (PET) resin film having optical transparency. A releasing film subjected to releasing treatment is bonded on the pressure-sensitive adhesive layer of the surface protective film until the pressure-sensitive adhesive layer is bonded to the optical member.

The optical member such as a polarizing plate is subjected to product inspection accompanied by optical evaluation such as display ability, color, contrast, foreign matter incorporation, etc. of the liquid crystal display panel in a state where the surface protective film is stuck.

For this reason, as the performance required for the surface protective film, it is required that the pressure-sensitive adhesive layer is free of bubbles and foreign substances and low molecular weight components of the pressure-sensitive adhesive composition, that is, has stain resistance.

Further, when peeling the surface protective film from an optical member such as a polarizing plate, peeling electrification caused by static electricity generated when the pressure sensitive adhesive layer peels from the adherend may affect the failure of the electric control circuit of the liquid crystal display . For this reason, the pressure-sensitive adhesive layer constituting the surface protective film is required to have excellent antistatic properties.

In recent years, as a polarizer protective layer (also referred to as a protective film) of a polarizing plate, an acrylic resin such as polymethylmethacrylate (PMMA), a polyolefin such as polyethylene terephthalate (PET), etc., in addition to conventional triacetylcellulose Based resins, ester-based resins, cyclic olefin-based polymers, and polycarbonate. Since the protective layer made of these materials tends to cause peeling electrification when the surface protective film adhered to the polarizing plate is peeled off, the pressure sensitive adhesive layer for the surface protective film of the polarizing plate is required to have excellent antistatic performance as compared with the conventional one.

In addition, when the surface protective film is finally peeled from an optical member such as a polarizing plate, it is necessary to be able to peel off quickly. It is required that there is little change in the adhesive force according to the peeling speed so that it can be rapidly peeled even by the so-called high-speed peeling.

In recent years, from the viewpoint of ease of use in the use of the surface protective film, there has been a demand for the pressure sensitive adhesive layer constituting the surface protective film as follows: (1) a balance between adhesive strength at low- (2) having stain resistance, and (3) excellent antistatic performance.

(1) to (3) required for the pressure-sensitive adhesive layer of the surface protective film can be obtained, although the respective required performance can be satisfied for each of the above requirements (1) to (3) ) At the same time, it was a difficult problem to satisfy. In addition, a material such as an acrylic resin such as polymethylmethacrylate (PMMA) other than TAC which is conventionally used as a protective layer material, a polyester resin such as polyethylene terephthalate (PET), a cyclic olefin polymer, or polycarbonate It was also a very difficult problem to form the pressure-sensitive adhesive layer of the surface protective film usable for the adopted protective layer surface and satisfying the required performance (1) to (3) from the same pressure-sensitive adhesive composition.

These problems can be solved by, for example, (1) having a balance of adhesive force at a low speed peeling speed and a high speed peeling speed, (2) having stain resistance, and (3) The following suggestions are known.

(1) With respect to those having a balance of adhesive force at a low rate of peeling and a high rate of peeling, a copolymer comprising a copolymer of a (meth) acrylic acid alkyl ester having an alkyl group having not more than 7 carbon atoms and a carboxyl group-containing copolymerizable compound as a main component, , There is a problem that the pressure-sensitive adhesive is adhered to the adherend when it is adhered for a long period of time, and the adhesiveness to the adherend increases with time. In order to avoid this, it is known to use a copolymer of a (meth) acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms and a copolymerizable compound having an alcoholic hydroxyl group, and to form a pressure-sensitive adhesive layer which is crosslinked with a crosslinking agent Patent Document 1).

It has also been proposed that a small amount of a copolymer of a (meth) acrylic acid alkyl ester and a carboxyl group-containing copolymerizable compound is added to the same copolymer as described above and a pressure-sensitive adhesive layer obtained by crosslinking the copolymer with a crosslinking agent is formed. However, when they are used for protecting the surface of a plastic plate or the like whose surface is smooth due to low surface tension, peeling phenomenon such as lifting due to heating at the time of processing or storage may occur. In addition, There was also a problem of poor sex.

In order to solve these problems, it is preferable that (a) 100 parts by weight of (a) a (meth) acrylic acid alkyl ester having a (meth) acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms as a main component, And c) 3 to 100 parts by weight of a vinyl ester of an aliphatic carboxylic acid having 1 to 5 carbon atoms is added to a copolymer of a monomer mixture containing a crosslinking agent in an equivalent amount or more with respect to the carboxyl group of the component b) (Patent Document 2).

In the pressure-sensitive adhesive composition described in Patent Document 2, peeling phenomenon such as peeling does not occur during processing or storage, and the peelability of the adhesive force with time is small, so that the peelable property is excellent and long- It is possible to re-peel by force, and no adhesive residue is formed on the adherend at this time, and even when high-speed peeling is performed, re-peeling is possible with a small force.

(2) those having stain resistance are those having a carboxyl group-containing monomer having a hydroxyl group content of less than 0.5 part by mass, a hydroxy group-containing (meth) acrylic monomer having a carboxyl group content of 0.6 to 9 parts, and a (meth) acrylic acid ester monomer having a mass ratio of 99.4 to 90.5 100 parts by weight of a (meth) acrylic copolymer having a weight average molecular weight of 100,000 or more and less than 1,000,000, and 0.1 to 5 parts by weight of a carbodiimide crosslinking agent (Patent Document 3).

In the pressure-sensitive adhesive composition described in Patent Document 3, a carbodiimide-based crosslinking agent is used as a crosslinking agent for a (meth) acrylic copolymer having a specific composition. This makes it possible to form a crosslinked structure in the pressure-sensitive adhesive layer that can follow the contraction due to the pressure and temperature during the autoclave treatment. Therefore, it is said that the pressure-sensitive adhesive layer formed by using the pressure-sensitive adhesive composition can inhibit / prevent foaming even under high temperature and high pressure conditions (during autoclave treatment), excellent in stain resistance to endophilic complexes, and excellent in transparency.

As to (3) excellent antistatic performance, a method for imparting antistatic property to the surface protective film is known, for example, a method in which an antistatic agent is contained in a base film.

Examples of the antistatic agent include (a) various cationic antistatic agents having cationic groups such as quaternary ammonium salts, pyridinium salts and primary to tertiary amino groups, (b) sulfonic acid bases, sulfuric acid ester bases, phosphoric acid esters (C) an amphoteric antistatic agent such as amino acid or amino sulfate ester, (d) a nonionic antistatic agent such as amino alcohol, glycerin or polyethylene glycol, An antistatic agent, and (e) a polymeric antistatic agent obtained by high-molecular weight the above antistatic agent, etc. (Patent Document 4).

In recent years, it has been proposed to incorporate such an antistatic agent into a base film or to include it in a pressure-sensitive adhesive layer without being coated on the surface of the base film.

The antistatic pressure-sensitive adhesive composition in which a salt having an anion having a fluoro group and a sulfonyl group is dispersed is characterized in that the salt having an anion having a fluoro group and a sulfonyl group is a polyether ester containing a polyether group in the main chain And dispersed in a state dissolved in a plasticizer (Patent Document 5).

In the pressure-sensitive adhesive composition described in Patent Document 5, an ester formed of a mono- or dicarboxylic acid having a saturated or unsaturated non-cyclic hydrocarbon group and an alcohol having a non-cyclic hydrocarbon group having 1 to 20 carbon atoms as the plasticizer, A plasticizer comprising an ester in which an unsaturated group in a hydrocarbon group is epoxidized is used. Such a mono- or dicarboxylic acid having a saturated or unsaturated non-cyclic hydrocarbon group has a carbon number close to the number of carbon atoms of the acrylic monomer constituting the acrylic copolymer used in the pressure-sensitive adhesive layer, so that compatibility with the antistatic pressure- Plasticizer Since it is preferably kept in the acrylic antistatic pressure-sensitive adhesive composition, bleed-out is suppressed.

Japanese Patent Application Laid-Open No. 63-225677 Japanese Laid-Open Patent Publication No. 11-256111 Japanese Laid-Open Patent Publication No. 2011-122054 Japanese Laid-Open Patent Publication No. 11-070629 Japanese Laid-Open Patent Publication No. 2014-118469

As described above, in the prior art, the pressure-sensitive adhesive layer constituting the surface protective film is required to have a balance of adhesive force at a low speed peeling speed and a high speed peeling speed, one having a stain resistance, And so on. However, even though each of the required performance can be satisfied, the required performance for the pressure-sensitive adhesive layer of the surface protective film can not all be satisfied at the same time.

Further, in the prior art, it has been impossible to produce a pressure-sensitive adhesive layer that can be used for all the surface base materials composed of TAC, PMMA, and PET, and simultaneously satisfies the required performance required for the pressure-sensitive adhesive layer of the surface protective film.

It is an object of the present invention to provide a pressure-sensitive adhesive composition and a surface-protective film which are excellent in balance of adhesive force at a low-speed peeling speed and a high-speed peeling speed, and also have stain resistance and excellent adhesive performance . It is also an object of the present invention to provide a pressure-sensitive adhesive composition and a surface protective film which can be used for a surface base material composed of TAC, PMMA and PET, and can form a pressure-sensitive adhesive layer having excellent antistatic properties without deterioration with time, from the same pressure- do.

In a pressure-sensitive adhesive composition having an antistatic property and a surface protective film using the same, the relationship between the antistatic property and the stain resistance to the adherend has a trade-off relationship, and the stain resistance is improved while maintaining the antistatic property It was very difficult.

Accordingly, the inventors of the present invention have found that a pressure-sensitive adhesive composition comprising a first acrylic polymer that does not contain a mono (meth) acrylic acid ester monomer containing a polyalkylene glycol chain and is copolymerized with a copolymerizable monomer containing a carboxyl group, (Meth) acrylate monomer having a fluorine atom-containing mono (meth) acrylate ester monomer, and preferably a polyether-containing silicone compound and a melting point 25 (a) having an anion having a fluorine atom number of not less than F7 (for example, nonafluorobutanesulfonate anion) Or more, and an antistatic agent composed of an ionic compound having a molecular weight of not less than < RTI ID = 0.0 > 1 C < / RTI >

In order to solve the above problems, the present invention provides a pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent and a crosslinking agent, wherein the acrylic polymer is a first acrylic polymer and a second acrylic polymer,

Wherein the first acrylic polymer comprises

(A) 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group having from 1 to 18 carbon atoms,

(B) 1.0 to 6.0 parts by weight in total of at least one copolymerizable monomer containing a hydroxyl group,

(C) 0.01 to 0.6 parts by weight of a total of at least one copolymerizable monomer containing a carboxyl group

(Meth) acrylate monomer containing no polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer and having an acid value of 0.1 to 1.0 and a weight average molecular weight of 300,000 to 1,200,000,

Wherein the first acrylic polymer contains 2-ethylhexyl acrylate in a proportion of 70 parts by weight or more among 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group of C1-C18 in the alkyl group Lt; / RTI &

Wherein the second acryl-based polymer comprises:

(a) at least one or more of (meth) acrylic acid ester monomers having an alkyl group having from 1 to 18 carbon atoms,

(b) at least one copolymerizable monomer containing a hydroxyl group, and

(c) at least one or more kinds of mono (meth) acrylic acid ester monomers containing polyalkylene glycol chain

A second acryl-based polymer of a copolymer obtained by copolymerization,

Wherein the glass transition temperature of the first acrylic polymer and the second acrylic polymer is 0 DEG C or lower,

Wherein the crosslinking agent is (D) an isocyanate compound having three or more functional groups,

Wherein the antistatic agent (G) is an ionic compound having a melting point of 25 to 50 캜 comprising a cation and an anion having an anion having a fluorine atom number of not less than F7,

Wherein the pressure-sensitive adhesive composition further comprises (E) a crosslinking retarder and (F) a crosslinking catalyst other than a tin compound as a crosslinking catalyst.

The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition for a surface protective film bonded to a polarizer protective layer of a polarizer, wherein the polarizer protective layer of the polarizer is one selected from the group consisting of a TAC film, a PMMA film, It is preferable that the surface treatment performed on the surface of the polarizer protective layer of the polarizing plate is one selected from the group consisting of untreated, AG treated, LR treated, AR treated, AG-LR treated and AG-AR treated.

Wherein the anions of ionic compounds _{C 6 F 5 (CF 2)} n COO -, C 6 F 5 (CF 2) n SO 3 -, C 6 F 5 (CF 2) n O -, C 6 F 5 O ( ^{_{CF 2) n SO 3 -,}} (C 6 F 5 CO) 2 N -, (C 6 F 5 CO) 3 C -, (C 6 F 5 SO 2) 2 N -, (C 6 F 5 SO 2) ^{_{3 C -, (C 6 F}} 5 OSO 2) 2 N -, (C 6 F 5 OSO 2) 3 C -, (C 6 F 5) 4 B -, CF 3 (CF 2) 3 SO 3 - consisting of And an ionic compound selected from the group consisting of anionic surfactant and anionic surfactant. The ionic compound is preferably contained in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the first acrylic polymer.

Wherein the cation of the ionic compound is selected from the group consisting of pyridinium, imidazolium, phosphonium, sulfonium, pyrrolidinium, guanidinium, ammonium, isooronium, thiouronium, piperidinium, pyrazolium, And morpholium, and it is preferable that the ionic compound is contained in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the first acryl-based polymer.

Peeling of the pressure-sensitive adhesive layer on the low refractive index layer formed by the surface resistivity of which the pressure-sensitive adhesive layer cross-linked to the pressure-sensitive adhesive composition is 1.0 × 10 ⁺¹² Ω / □ or less, using a composition for forming a low refractive index layer containing a fluorine compound to the deposition surface The adhesive strength of the pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition within a range of -0.3 to +0.04 kV with a large voltage of 0.04 to 0.2 N / 25 mm at a low speed peeling rate of 0.3 m / min to the polarizing plate, It is preferable that the adhesive force at 30 m / min is 2.0 N / 25 mm or less.

Wherein the copolymerizable monomer containing the hydroxyl group of the first acrylic polymer and the copolymerizable monomer containing the hydroxyl group of the second acrylic polymer are selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, Hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, (Meth) acrylic acid, carboxyethyl (meth) acrylate, and N-hydroxyethyl (meth) acrylamide, wherein the copolymerizable monomer containing a carboxyl group is at least one selected from the group consisting of (Meth) acryloyloxyethyl methacrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (Meth) acryloyloxyethyl methacrylate, 2- (meth) acryloyloxyethyl succinic acid, carboxypolycaprolactone mono (meth) acrylate and 2- (meth) acryloyloxyethyl tetrahydrophthalic acid. At least one kind selected from among them.

Wherein the crosslinking retarder (E) is a keto-isothiocyanate compound, and the crosslinking retarder (E) is contained in an amount of 0.1 to 300 parts by weight based on 100 parts by weight of the first acrylic polymer, Wherein the crosslinking catalyst is at least one metal chelate compound selected from the group consisting of an aluminum chelate compound, a titanium chelate compound and an iron chelate compound, and the above (F) crosslinking catalyst is added in an amount of 0.001 to 0.5 wt. (E) / (F) is preferably 80 to 1000 parts by weight.

It is preferable that the pressure-sensitive adhesive composition contains a polyether-modified siloxane compound having an HLB value of 6 to 12 and a weight-average molecular weight of 10000 or less in a proportion of 0.01 to 0.5 parts by weight based on 100 parts by weight of the first acrylic polymer.

Wherein the pressure-sensitive adhesive composition comprises the second acrylic polymer in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the first acrylic polymer, and the second acrylic polymer comprises (a) the alkyl group has a C1- (B) 2.0 to 12.0 parts by weight in total of at least one copolymerizable monomer containing a hydroxyl group, based on 100 parts by weight of the total of at least one kind of (meth) acrylic acid ester monomer, and (c) a polyalkylene glycol chain- (Meth) acrylic acid ester monomer in a total amount of 1 to 30 parts by weight. The weight average molecular weight of the copolymer is preferably from more than 300,000 to 1,000,000, particularly preferably from 300,000 to 800,000.

(B) at least one kind of a copolymerizable monomer containing a hydroxyl group, based on 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group of C1-C18 in the alkyl group of the first acrylic polymer, (Meth) acrylic acid ester monomer having an alkyl group of C1 to C18 in the total amount of 100 parts by weight of the second acrylic polymer (a) and the total weight part (? 1 = 100 x (B) / (K =? 2 /? 1) of the total weight part (? 2 = 100 x (b) / (a)) of at least one kind of copolymerizable monomers containing a hydroxyl group (b) .

Wherein the second acrylic polymer is a copolymer having a weight average molecular weight of 300,000 or more and 800,000 or less, wherein the polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer has an average number of repeating alkylene oxides constituting the polyalkylene glycol chain (Meth) acrylic ester monomers having a polyalkylene glycol chain containing mono (meth) acrylic acid ester monomer having a diester content of 0.2% or less and a polyalkylene glycol mono (Meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, and ethoxypolyalkylene glycol (meth) acrylate in an amount of 1 to 50 parts by weight per 100 parts by weight of the second acrylic polymer By weight, more preferably 1 to 40 parts by weight, further preferably 1 to 30 parts by weight The addition is particularly preferred.

Further, the present invention provides an adhesive film characterized in that a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition on one side of a resin film is laminated.

The present invention also provides a surface protective film using the adhesive film.

Further, the present invention provides a surface protective film for a polarizing plate using the above-mentioned pressure-sensitive adhesive film.

The present invention also provides an optical film in which a pressure-sensitive adhesive layer in which a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition is laminated on at least one surface of an optical film is provided.

Further, the present invention provides an adhesive film in which an antistatic treatment and an antifouling treatment are performed on a side of the resin film one side opposite to the side where the pressure-sensitive adhesive layer is formed.

According to the present invention, it is possible to provide a pressure-sensitive adhesive composition and a surface-protective film excellent in balance of adhesive force at a low speed peeling speed and a high speed peeling speed, and also having stain resistance and excellent adhesive performance. Also, it is possible to provide a pressure-sensitive adhesive composition and a surface-protective film which can be used for a surface base material composed of TAC, PMMA and PET, and can form a pressure-sensitive adhesive layer having excellent antistatic properties without degradation with time, from the same pressure-

Hereinafter, the present invention will be described based on preferred embodiments.

The pressure-sensitive adhesive composition of the present embodiment is a pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent and a crosslinking agent, wherein the acrylic polymer is a first acrylic polymer and a second acrylic polymer,

Wherein the first acrylic polymer comprises

(A) 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group having from 1 to 18 carbon atoms,

(B) 1.0 to 6.0 parts by weight in total of at least one copolymerizable monomer containing a hydroxyl group,

(C) 0.01 to 0.6 parts by weight of a total of at least one copolymerizable monomer containing a carboxyl group

(Meth) acrylate monomer containing no polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer and having an acid value of 0.1 to 1.0 and a weight average molecular weight of 300,000 to 1,200,000,

Wherein the first acrylic polymer contains 2-ethylhexyl acrylate in a proportion of 70 parts by weight or more among 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group of C1-C18 in the alkyl group Lt; / RTI &

Wherein the second acryl-based polymer comprises:

(a) at least one or more of (meth) acrylic acid ester monomers having an alkyl group having from 1 to 18 carbon atoms,

(b) at least one copolymerizable monomer containing a hydroxyl group, and

(c) at least one or more kinds of mono (meth) acrylic acid ester monomers containing polyalkylene glycol chain

A second acryl-based polymer of a copolymer obtained by copolymerization,

Wherein the glass transition temperature of the first acrylic polymer and the second acrylic polymer is 0 DEG C or lower,

Wherein the crosslinking agent is (D) an isocyanate compound having three or more functional groups,

Wherein the antistatic agent (G) is an ionic compound having a melting point of 25 to 50 캜 comprising a cation and an anion having an anion having a fluorine atom number of not less than F7,

Wherein the pressure-sensitive adhesive composition further comprises (E) a crosslinking retarder and (F) a crosslinking catalyst other than a tin compound as a crosslinking catalyst.

Compared with the conventional pressure-sensitive adhesive composition for a surface protective film, the pressure-sensitive adhesive composition according to the present embodiment has excellent adhesion performance and excellent peeling electrification preventing performance without deterioration over time.

In particular, the surface protective film according to the present embodiment uses a composition for forming an antifouling layer containing a fluorine compound on the surface of an optical film or the like on which an adherend such as an optical film is to be adhered, or a composition for forming a low refractive index layer containing a fluorine compound Refractive-index layer formed by laminating a low-refractive-index layer formed by laminating a low-refractive-index layer and a low-refractive-index layer formed thereon, Effect.

That is, the pressure-sensitive adhesive composition according to the present embodiment and the surface protective film using the pressure-sensitive adhesive composition of the present invention have excellent adhesive performance and excellent peeling electrification preventing performance without deterioration over time, and thus are of great industrial value.

The acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment is a subject polymer of the pressure-sensitive adhesive composition and has a glass transition temperature of 0 占 폚 or less. The acrylic polymer is preferably a copolymer having (A) a (meth) acrylic acid ester monomer having an alkyl group having from 1 to 18 carbon atoms as a main component.

The acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment contains a first acrylic polymer not containing a mono (meth) acrylic acid ester monomer containing a polyalkylene glycol chain and a second acrylic polymer containing a mono (meth) acrylic acid ester monomer containing a polyalkylene glycol chain Based polymer.

The first acrylic polymer is obtained by copolymerizing (A) a copolymerizable monomer containing a (meth) acrylic acid ester monomer having an alkyl group of C1 to C18, (B) a copolymerizable monomer containing a hydroxyl group, and (C) (Meth) acrylate monomer containing no phenolic hydroxyl group and a phenolic hydroxyl group, and having a glass transition temperature of 0 占 폚 or less. (B) at least one copolymerizable monomer containing a hydroxyl group, and (c) at least one monomer selected from the group consisting of (c) at least one (meth) acrylic acid ester monomer having an alkyl group having from 1 to 18 carbon atoms, ) Polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomers, and has a glass transition temperature of 0 占 폚 or lower.

Examples of the (meth) acrylate monomer having (a) the alkyl group of C1-C18 in the (meth) acrylate monomer having an alkyl group of the C1-C18 alkyl group and the second acryl- (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl Acrylates such as octyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (Meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, undecyl (meth) acrylate, Heptadecyl ( L) acrylate, octadecyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate. The alkyl group of the alkyl (meth) acrylate monomer may be linear, branched or cyclic.

The first acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment is a polymer obtained by copolymerizing 2-ethylhexyl acrylate with 70 (meth) acrylic acid ester monomer By weight or more.

The first acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment contains (B) a copolymerizable monomer containing a hydroxyl group. Further, the second acrylic polymer contains (b) a copolymerizable monomer containing a hydroxyl group. Examples of the copolymerizable monomer containing (B) the hydroxyl group of the first acrylic polymer and the hydroxyl group of the second acrylic polymer (b) include copolymerizable monomers such as 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (Meth) acrylate, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylate, -Hydroxyethyl (meth) acrylamide, and the like.

The first acrylic polymer preferably has a total of 1.0 or more of at least one copolymerizable monomer containing (B) a hydroxyl group, based on 100 parts by weight of the total of at least one (meth) acrylate monomer having (A) To 6.0 parts by weight, more preferably from 1.6 to 5.8 parts by weight, and particularly preferably from 2.1 to 5.8 parts by weight.

(B) a total of at least one copolymerizable monomer containing a hydroxyl group is 2.0 (meth) acrylate monomer based on 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group of C1- To 12.0 parts by weight, more preferably in a proportion of 3.0 to 11.0 parts by weight, and particularly preferably in a proportion of 4.0 to 10.0 parts by weight.

The total weight part? 1 of at least one copolymerizable monomer containing a hydroxyl group in the first acrylic polymer (B) is preferably a combination of (A) at least one or more (meth) acrylic acid ester monomers having an alkyl group of C1- (B) / (A) with respect to 100 parts by weight in total. Similarly, the total weight part? 2 of at least one copolymerizable monomer containing a hydroxyl group (b) in the second acrylic polymer is (a) at least one (meth) acrylic acid ester monomer having an alkyl group having from 1 to 18 carbon atoms (100) (b) / (a) with respect to 100 parts by weight of the total of at least 100 kinds. (B) of the second acrylic polymer is preferably at least 1 part by weight of (B) in the first acrylic polymer, and the ratio (K =? 2 /? 1) is in the range of 1.0 to 2.0 desirable.

The first acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment contains (C) a copolymerizable monomer containing a carboxyl group. Examples of the copolymerizable monomer containing a carboxyl group (C) include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (Meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- Caprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyltetrahydrophthalic acid, and the like.

The first acrylic polymer is a copolymer of (A) a total of at least one copolymerizable monomer containing a carboxyl group (C) per 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group of C1- More preferably 0.01 to 0.5 parts by weight, and particularly preferably 0.01 to 0.4 parts by weight.

The second acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment contains (c) a mono (meth) acrylic acid ester monomer containing a polyalkylene glycol chain. Therefore, in the pressure-sensitive adhesive composition of the present embodiment, it is considered that the second acrylic polymer containing the (meth) acrylic acid ester monomer containing a polyalkylene glycol chain (c) functions as an antistatic auxiliary agent. The second acrylic polymer is preferably contained in a proportion of 0.1 to 5.0 parts by weight, more preferably 0.1 to 3.5 parts by weight, and more preferably 0.1 to 2.5 parts by weight, based on 100 parts by weight of the first acrylic polymer. Is particularly preferable.

When the content of the second acrylic polymer is less than the above range, the surface resistivity and the peeling electrification voltage become high, and the antistatic performance deteriorates. Further, the stain resistance to the polarizing plate is poor.

(c) The polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer may be any compound in which one of the hydroxyl groups of the polyalkylene glycol is esterified as a (meth) acrylic acid ester. (Meth) acrylic acid ester group becomes a polymerizable group, it can be copolymerized with the second acrylic polymer. (Meth) acrylate in which the other hydroxyl groups are as OH, and alkoxypolyalkylene glycol mono (meth) acrylates in which other hydroxyl groups are converted into alkyl ethers. On the other hand, the polyalkylene glycol mono (meth) acrylate is not classified into (B) or (b) even if it contains a hydroxyl group, from the point of correspondence to (c).

The polyalkylene glycol constituting the polyalkylene glycol chain may be any glycol compound having one or more alkylene groups, and examples thereof include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol-polypropylene Glycols, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, polyethylene glycol-polypropylene glycol-polybutylene glycol, and the like.

(c) The average number of repeats of the alkylene oxide constituting the polyalkylene glycol chain of the mono (meth) acrylic acid ester monomer containing the polyalkylene glycol chain is preferably 3 to 14. Means the average number of repeating alkylene oxide units in the " polyalkylene glycol chain " moiety contained in the molecular structure of the mono (meth) acrylic acid ester monomer containing the polyalkylene glycol chain ≪ / RTI >

The diester content in the mono (meth) acrylic acid ester monomer (c) containing the polyalkylene glycol chain is preferably 0.2% or less. The "diester content in the monomer" is the content (% by weight) of the polyalkylene glycol di (meth) acrylic acid ester contained in the (c) mono (meth) acrylic acid ester monomer containing the polyalkylene glycol chain.

(meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, ethoxypolyalkylene glycol (meth) acrylate, and methoxypolyalkylene glycol (meth) Acrylate, and the like. The ratio of the mono (meth) acrylic acid ester monomer containing the polyalkylene glycol chain (c) in the second acrylic polymer is preferably from 1 to 50 parts by weight, more preferably from 2 to 35 parts by weight, based on 100 parts by weight of the second acrylic polymer , And a ratio of 2 to 25 parts by weight is particularly preferable.

(C) a polyalkylene glycol mono (meth) acrylate mono (meth) acrylate ester having a polyalkylene glycol chain containing mono (meth) acrylic acid ester monomer as the polyalkylene glycol mono (meth) acrylate, methoxy polyalkylene glycol (meth) acrylate, ethoxy polyalkylene glycol ) Acrylate in an amount of 1 to 50 parts by weight, preferably 1 to 40 parts by weight, more preferably 1 to 30 parts by weight, based on 100 parts by weight of the second acrylic polymer Particularly preferred.

(C) at least one (meth) acrylic ester monomer containing at least one polyalkylene glycol chain containing mono (meth) acrylic acid ester monomer, based on 100 parts by weight of the total of at least one (meth) acrylic acid ester monomer having It is preferable that the total amount of the species is 1 to 30 parts by weight.

Examples of the monomer other than the polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer copolymerized with the second acrylic polymer include (a) a (meth) acrylic ester monomer having an alkyl group of C1- b) a copolymerizable monomer containing a hydroxyl group, and the like. The monomers (a) and (b) copolymerized with the second acrylic polymer may be different from the monomers (A) and (B) copolymerized with the first acrylic polymer. The second acrylic polymer may not copolymerize a copolymerizable monomer containing a carboxyl group.

The method of producing the acrylic polymer to be contained in the pressure-sensitive adhesive composition according to the present embodiment is not particularly limited, and a well-known polymerization method such as a solution polymerization method and an emulsion polymerization method can be used. The weight average molecular weight of the copolymer of the first acrylic polymer is, for example, from 300,000 to 1,200,000. The weight average molecular weight of the copolymer of the second acrylic polymer is, for example, from more than 300,000 to less than 1,000,000, preferably from 300,000 to 800,000, and more preferably from 400,000 to 800,000.

When the weight average molecular weight of the copolymer of the second acryl-based polymer is less than 300,000, the stain resistance to the polarizing plate is poor, which is not preferable.

The acid value of the first acrylic polymer is preferably 0.1 to 1.0. Thus, the stain resistance can be improved. Here, " acid value " is an indicator of the content of acid and is expressed by the number of mg of potassium hydroxide necessary for neutralizing 1 g of a carboxyl group-containing polymer. The acid value of the second acrylic polymer is preferably 1.0 or less, and may be 0.0 when the copolymerizable monomer containing a carboxyl group is not copolymerized with the second acrylic polymer.

The pressure-sensitive adhesive composition according to the present embodiment contains (G) an antistatic agent. The antistatic agent (G) of the present embodiment is an ionic compound comprising a cation and an anion having an anion having a fluorine atom number of not less than F7. The ionic compound preferably has a melting point of 25 to 50 캜 and is a solid at normal temperature (for example, 25 캜). The ionic compound is preferably contained in an amount of 0.01 to 15 parts by weight, more preferably 0.01 to 10 parts by weight, and particularly preferably 0.01 to 8 parts by weight, based on 100 parts by weight of the first acrylic polymer.

As the anion of the ionic _{compound, C 6 F 5 (CF 2} ) n COO -, C 6 F 5 (CF 2) n SO 3 -, C 6 F 5 (CF 2) n O -, C 6 F 5 _{O (CF 2) n SO 3} -, (C 6 F 5 CO) 2 N -, (C 6 F 5 CO) 3 C -, (C 6 F 5 SO 2) 2 N -, (C 6 F 5 SO ^{_{2) 3 C -, (C}} 6 F 5 OSO 2) 2 N -, (C 6 F 5 OSO 2) 3 C -, (C 6 F 5) 4 B -, CF 3 (CF 2) 3 SO 3 - At least one kind selected from the group consisting of Here, n is an integer of 1 or more.

Examples of the cation of the ionic compound include pyridinium, imidazolium, phosphonium, sulfonium, pyrrolidinium, guanidinium, ammonium, isooronium, thiouronium, piperidinium, pyrazolium, Lithium, and molybdenum may be cited.

Specific examples of the antistatic agent (G) include, for example, methyltrioctylammonium tris (pentafluorobenzenesulfonyl) methide salt, 3-methyl-1-octylpyridinium nonafluorobutanesulfonate salt, 1- Ethyl-3-methylimidazolium tetrakispentafluorophenylborate salt, and 1-butyl-1-methylpiperidinium bis (pentafluorobenzenesulfonyl) imide salt.

The pressure-sensitive adhesive composition according to the present embodiment further contains (D) an isocyanate compound having three or more functional groups as a crosslinking agent. Examples of the isocyanate compound having three or more functional groups (D) include biuret-modified products of diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate and xylylene diisocyanate, Modified substances, trimethylol propane, and adducts with tri- or higher-valent polyols such as glycerin. The ratio of the (D) trifunctional or higher isocyanate compound may be, for example, from 0.01 to 5 parts by weight based on 100 parts by weight of the first acrylic polymer.

The pressure-sensitive adhesive composition according to the present embodiment may contain (E) a crosslinking retarder. (E) As the crosslinking retarder, β-keto esters such as methyl acetoate, ethyl acetoate, octyl acetoate, oleyl acetoacetate, lauryl acetoacetate and stearyl acetoate, acetyl acetone, 2,4-hexanedione , And benzoyl acetone. These are keto-enolic tautomeric compounds, and in the pressure-sensitive adhesive composition using the polyisocyanate compound as a crosslinking agent, blocking of the isocyanate group of the crosslinking agent inhibits increase in the excess viscosity or gelation of the pressure-sensitive adhesive composition after blending of the crosslinking agent, You can extend your life. The crosslinking retarder (E) is preferably a ketoene glycol isomer compound, more preferably at least one member selected from the group consisting of acetylacetone and ethyl acetoacetate. It is preferred that the crosslinking retarder (E) is contained in an amount of 0.1 to 300 parts by weight based on 100 parts by weight of the first acrylic polymer.

The pressure-sensitive adhesive composition according to the present embodiment may contain (F) a crosslinking catalyst other than a tin compound as a crosslinking catalyst. (F) The crosslinking catalyst may be a substance that functions as a catalyst for the reaction (crosslinking reaction) between the copolymer and the crosslinking agent when the polyisocyanate compound is used as the crosslinking agent. As the crosslinking catalyst other than the tin compound, an amine compound such as a tertiary amine, an organic metal compound such as a metal chelate compound, an organic lead compound, an organic zinc compound and the like can be given.

(F) As the metal chelate compound of the crosslinking catalyst, there is a compound in which at least one Brillouin ligand L is bonded to the central metal atom M. The metal chelate compound may or may not have at least one monocyclic ligand X bonded to the metal atom M. Specific examples of the metal chelate compound include tris (2,4-pentanedionate) iron (III), iron trisacetylacetonate, titanium trisacetylacetonate, ruthenium trisacetylacetonate, zinc bisacetylacetonate, aluminum tris (2,4-hexanedionate) iron (III), bis (2,4-hexanedionate) zinc, tris (2,4-hexanedionate) titanium, Tris (2,4-hexanedionate) aluminum, tetrakis (2,4-hexanedionate) zirconium, and the like.

(F) The crosslinking catalyst is preferably at least one metal chelate compound selected from the group consisting of an aluminum chelate compound, a titanium chelate compound and an iron chelate compound. (F) a crosslinking catalyst in an amount of 0.001 to 0.5 parts by weight based on 100 parts by weight of the first acrylic polymer.

It is preferable to appropriately set the ratio of the (E) crosslinking retarder to the crosslinking catalyst (F) in that the crosslinking retarder (E) has an effect of inhibiting crosslinking in contrast to the (F) crosslinking catalyst. In order to lengthen the pot life of the pressure-sensitive adhesive composition and improve the storage stability, it is preferable that the weight ratio of (E) / (F) is 80 to 1000. Here, the weight parts ratio of (E) / (F) is a quotient value obtained by dividing the weight part of (E) by the weight part of (F).

The pressure-sensitive adhesive composition according to the present embodiment may contain (H) a polyether-modified siloxane compound as an optional component. (H) a polyether-modified siloxane compound is a siloxane compound having a polyether, a typical siloxane unit [-SiR ¹ ₂ -O-] In addition, the siloxane units having polyether ^{[-SiR 1 (R 2 O (} R 3 O ) _n R ⁴ ) -O-]. (Wherein R ¹ represents one or two or more kinds of alkyl groups or aryl groups, R ² and R ³ represent one or two or more kinds of alkylene groups, and R ⁴ represents one or two or more kinds of alkyl groups or acyl groups . Examples of the polyether group include polyoxyalkylene groups such as a polyoxyethylene group [(C ₂ H ₄ O) _n ] and a polyoxypropylene group [(C ₃ H ₆ O) _n ]. In the siloxane unit having a polyether group, the terminal of the polyether group may be an OH group (R ⁴ = H in the above general formula).

(H) The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 6 to 12. The polyether-modified siloxane compound (H) is preferably contained in an amount of 0.01 to 0.5 parts by weight, more preferably 0.02 to 0.35 parts by weight, and most preferably 0.02 to 0.25 part by weight per 100 parts by weight of the first acrylic polymer Ratio is particularly preferred. The HLB value is, for example, a hydrophilic lipophilic balance (hydrophilic lipophilic ratio) defined in JIS K3211 (surfactant term).

The polyether-modified siloxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane main chain having a hydrogenated silicon group by a hydrosilylation reaction. Specific examples thereof include dimethylsiloxane · methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane · methyl (polyoxyethylene) siloxane · methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane · methyl (polyoxypropylene) .

(H) The polyether-modified siloxane compound is compounded in the pressure-sensitive adhesive composition, whereby the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer can be improved. The weight average molecular weight of the (H) polyether-modified siloxane compound is preferably 10,000 or less. From the standpoint of compatibility with the first acrylic polymer, the HLB value is low and the molecular weight is low. The polyether-modified siloxane compound having a low molecular weight has a relatively high HLB value and a good compatibility with the polymer, Prevention property is obtained.

The pressure-sensitive adhesive composition of the present embodiment is not limited to the above-described additives, but may be suitably blended with known additives such as surfactants, curing accelerators, plasticizers, fillers, curing retarders, processing aids, antioxidants and antioxidants. These may be used alone or in combination of two or more.

The pressure-sensitive adhesive composition of the present embodiment is preferable as a pressure-sensitive adhesive composition for a surface protective film to be bonded to a polarizer protective layer of a polarizing plate. Here, the polarizer protective layer of the polarizing plate may be at least one selected from the group consisting of a TAC film, a PMMA film, and a PET film. Here, TAC is triacetyl cellulose, PMMA is polymethyl methacrylate, and PET is an abbreviation of polyethylene terephthalate. The pressure-sensitive adhesive composition of the present embodiment may be made usable to three or more kinds of surface materials made of TAC, PMMA, and PET by the same pressure-sensitive adhesive layer.

The surface treatment performed on the surface of the polarizer protective layer of the polarizing plate may be at least one selected from the group consisting of untreated, AG treated, LR treated, AR treated, AG-LR treated and AG-AR treated. Here, AG is Anti Glare, LR is Low Reflection, and AR is Anti Reflection. The pressure-sensitive adhesive composition of the present embodiment is a pressure-sensitive adhesive composition in which the substrate on the surface of the polarizing plate is PMMA or PET and improves the stain resistance of at least one of AG, LR, AR, AG-LR and AG- .

A pressure-sensitive adhesive layer crosslinked pressure-sensitive adhesive composition of the present embodiment the surface resistivity of the pressure-sensitive adhesive layer 1.0 × 10 ⁺¹² Ω / □ or less is preferable, and, 5.0 × 10 ⁺¹¹ Ω / □ more preferably not more than, and 1.0 × 10 ⁺¹¹ Ω / □ Or less. If the surface resistivity is large, the performance of releasing the static electricity generated when the pressure-sensitive adhesive layer is peeled from the adherend is poor. Therefore, by sufficiently reducing the surface resistivity, it is possible to suppress the peeling electrification voltage, which is caused by the static electricity generated when the adhesive layer is peeled from the adherend, from being affected by the adherend.

The pressure-sensitive adhesive layer to which the pressure-sensitive adhesive composition of the present embodiment is crosslinked has a peeling electrification voltage of -0.3 to +0.0 kV in the pressure-sensitive adhesive layer for the low-refractive index layer formed by using the composition for forming a low- It is preferable that it is mine. Examples of the fluorine compound used in the composition for forming a low refractive index layer include fluorine-containing copolymers such as fluorinated olefins, fluorinated vinyl ethers, fluorinated alkyl (meth) acrylates, and the like, . The fluorine-containing copolymer may be copolymerized with an unsaturated monomer such as olefins, vinyl ethers, and (meth) acrylate in addition to the fluorinated monomer. The low refractive index layer may be combined with the high refractive index layer to constitute the antireflection layer.

The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of the present embodiment had a pressure-sensitive adhesive force of 0.04 to 0.2 N / 25 mm at a low speed peeling rate of 0.3 m / min and a pressure-sensitive adhesive force of 2.0 N / 25 Mm or less, and more preferably 0.2 to 1.6 N / 25 mm at a high-speed peeling speed of 30 m / min. As a result, it is possible to obtain a small change in the adhesive force depending on the peeling speed, and it is possible to peel quickly even by high-speed peeling. Further, even when the surface protective film is once peeled off for reattachment, it is easy to peel off the adherend without requiring an excessive force.

The gel fraction of the pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present embodiment is preferably 95 to 100%, more preferably 97 to 100%. As described above, the gel fraction is so high that the adhesive force is not excessively high at a low rate of peeling, and the elution of the unpolymerized monomer or oligomer from the copolymer is reduced to improve the durability in reworkability, high temperature and high humidity, Can be suppressed.

The pressure-sensitive adhesive film of the present embodiment is formed by forming a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition of the present embodiment is cross-linked, on one side or both sides of a resin film. The surface protective film of the present embodiment is a surface protective film formed by forming a pressure-sensitive adhesive layer crosslinked with the pressure sensitive adhesive composition of the present embodiment on one side of a resin film. The pressure-sensitive adhesive composition of the present embodiment has an excellent antistatic property, has excellent balance of adhesive force at a low speed peeling speed and a high speed peeling speed, and has stain resistance. Therefore, it can be preferably used as a surface protective film of a polarizing plate.

As the release film (separator) for protecting the substrate film or the adhesive surface of the pressure-sensitive adhesive layer, a resin film such as a polyester film or the like can be used.

The antistatic treatment and the antifouling treatment may be performed on the side opposite to the side where the pressure-sensitive adhesive layer is formed on one side of the resin film. Examples of the antistatic treatment include application and incorporation of an antistatic agent. Examples of the antifouling treatment include treatment with silicone, fluorine-type mold release agent, coating agent, fine silica particles and the like. The releasing film may be subjected to releasing treatment by a silicone-based, fluorine-based, long-chain alkyl-based releasing agent or the like on the side of the side of the pressure-

Further, an optical film on which a pressure-sensitive adhesive layer is formed can be obtained by laminating a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present embodiment on at least one side of the optical film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an antiglare film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensating film, and a brightness improving film. Examples of the device to which the optical member is applied include a liquid crystal panel, an organic EL panel, and a touch panel.

In the case of optical surface protective films such as surface protective films for polarizing plates and adhesive films, it is preferable that the base film and the pressure-sensitive adhesive layer have sufficient transparency.

Example

Hereinafter, the present invention will be described in detail with reference to Examples.

≪ Preparation of first acrylic polymer &

[Example 1]

Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube to replace the air in the reactor with nitrogen gas. Subsequently, a solvent (ethyl acetate) was added to the reaction apparatus together with 90 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of methyl acrylate, 5.5 parts by weight of 8-hydroxyoctyl acrylate, and 0.2 parts by weight of acrylic acid. Thereafter, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours and reacted at 65 DEG C for 6 hours to obtain a first acrylic polymer used in Example 1. [

[Examples 2 to 6 and Comparative Examples 1 to 3]

The same procedure as in the case of the first acrylic polymer solution used in Example 1 was carried out except that the monomers were changed as shown in Table 1 (A) to (C), respectively. In Examples 2 to 6 and Comparative Examples 1 to 3 A first acrylic polymer solution was obtained.

≪ Preparation of pressure-sensitive adhesive composition and surface protective film &

[Example 1]

2.0 parts by weight of a crosslinking agent (Coronate HX), 9 parts by weight of a crosslinking retarder (acetylacetone), 0.1 part by weight of a crosslinking catalyst (titanium trisacetylacetonate) 0.9 part by weight of an antistatic agent (methyltrioctylammonium tris (pentafluorobenzenesulfonyl) methide salt), 0.05 part by weight of polyether-modified siloxane compound (HLB = 7), 0.2 part by weight of copolymer B- And the mixture was stirred and mixed to obtain the pressure-sensitive adhesive composition of Example 1. This pressure-sensitive adhesive composition was coated on a release film (PET film coated with a silicone resin) and dried at 90 캜 to remove the solvent to obtain a pressure-sensitive adhesive layer having a thickness of 20 탆. Thereafter, a pressure-sensitive adhesive layer having a release film formed on the surface opposite to the antistatic and antifouling treated surface of the base film (the antistatic and anti-fouling PET film on one side) was transferred to form a base film / pressure- Film " in Example 1 was obtained.

[Examples 2 to 6 and Comparative Examples 1 to 3]

The surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3 were prepared in the same manner as in the surface protective film of Example 1 except that the additives were changed as described in (D) to (H) and (B) Of the surface protective film.

In Table 1, parts by weight of each component were determined by taking the total of (A) the (meth) acrylic acid ester monomer having C1-C18 alkyl groups as 100 parts by weight. On the other hand, "I-2" in Comparative Example 2 is described in the column (A) for convenience, but (A) does not correspond to a (meth) acrylic acid ester monomer in which the alkyl group has from 1 to 18 carbon atoms.

On the other hand, in each column of (D), (E), (F), (G), (H) and (B) in Table 1, the content of each component Parts by weight) are expressed in numerical values in parentheses ().

Tables 2 to 3 show the compound names of the weak symbols of each component used in Table 1. (A), (B), (I), (B) and (C) have the same meanings as those of the component monomers ). On the other hand, Coronate (registered trademark) HX, HL and L are trade names of Tohso Co., Ltd., and Takenate (trade mark) D-140N is trade name of Mitsui Chemicals,

Among the antistatic agents (G), G-1 to G-4 are all solid ionic compounds having an anion having a fluorine atom number of not less than F7 and a melting point of not less than 25 占 폚. G-5 is a solid ionic compound having an anion having a fluorine atom number of F5 and a melting point of 25 ° C or higher.

H-1 to H-6 in the (H) polyether-modified siloxane compound all have a weight average molecular weight of 10,000 or less.

I-1 to I-3 of the polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer have a diester content of 0.2% or less in the monomer, and I-4 has a diester content in the monomer of 0.8%. In the column (I) of Table 3, n is a numerical value representing the average number of repeating alkylene oxides.

<Test Method and Evaluation>

The surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3 were each aged for 7 days under an atmosphere of 23 ° C and 50% RH, and then evaluated by the following test methods.

<Test Method of Adhesive Force>

The releasing film was peeled off and a surface protecting film on which the pressure-sensitive adhesive layer was exposed was adhered to the surface of the polarizing plate via the pressure-sensitive adhesive layer. The plate was allowed to stand for one day, autoclaved at 50 DEG C and 5 atm for 20 minutes, Was used as a measurement sample of the adhesive force. The obtained measurement sample was peeled off at a low speed (0.3 m / min) or a high speed (30 m / min) using a tensile tester in the direction of 180 °.

Here, the polarizer protective layer of the polarizing plate is one selected from the group consisting of triacetyl cellulose (TAC), polymethyl methacrylate (PMMA), and polyethylene terephthalate (PET).

Further, in the LR polarizer and the AG-LR polarizer, the surface of the polarizer protective layer of the polarizing plate contains a fluorine compound and is subjected to a low-reflection surface treatment.

<Test Method of Surface Resistivity>

After the surface protective film was aged, the release film was peeled off before bonding to the polarizing plate to expose the pressure-sensitive adhesive layer, and the surface resistivity of the pressure-sensitive adhesive layer was measured using a resistivity meter HILESTA UP-HT450 (manufactured by Mitsubishi Chemical Engineering Co., Ltd.) .

<Test Method of Peeling Voltage>

A releasing film was peeled off to form a pressure-sensitive adhesive layer, and a surface protective film was applied to a polarizing plate having a low refractive index layer formed by using a composition for forming a low refractive index layer containing a fluorine compound on the adherend surface. When the surface protective film was peeled 180 ° at a tensile speed of 30 m / min, the voltage (voltage) generated by charging the adherend was measured using a high-precision static electricity sensor SK-035, SK-200 (manufactured by Keyence Corporation) And the maximum value of the measured value was taken as the peeling voltage.

&Lt; Test method of stain resistance &gt;

Each polarizing plate selected from the five types shown in Table 4 was bonded on one side of the glass plate via a pressure-sensitive adhesive layer (double-faced pressure-sensitive adhesive tape) using a coater. Thereafter, a surface protective film was applied to each polarizing plate surface using a coater. After storage for 3 days and 30 days in an environment of 23 ° C and 50% RH, the surface protective film was peeled off and the contamination state of the surface of the polarizing plate was visually observed. The criteria for stain resistance were evaluated as &quot;? &Quot;, &quot;? &Quot;, and &quot; x &quot;, respectively.

Table 4 shows the evaluation results of the surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3. The &quot; surface resistivity &quot; is expressed in accordance with a method (m is an arbitrary real number value and n is a positive integer) in which "m x 10 ^{+ n} " is set to "mE + n". The term &quot; stain resistance (surface material / surface treatment) &quot; shows the evaluation results of the material and the surface treatment of the five types of polarizing plate surface substrates (polarizer protective layer). "Plain" means "untreated".

The surface protective films of Examples 1 to 6 had an adhesive force of 0.04 to 0.2 N / 25 mm at a low speed peeling rate of 0.3 m / min and an adhesive force of 2.0 N / 25 mm Or less.

In Examples 1 to 6, a surface protecting film is the surface resistivity of the pressure-sensitive adhesive layer 1.0 × 10 ⁺¹² Ω / □ or less, the low refractive index layer is formed using a composition for forming a low refractive index layer containing a fluorine compound to the deposition surface The peeling electrification voltage of the pressure-sensitive adhesive layer was within the range of -0.3 to +0.3 kV, and the antistatic performance was excellent.

In addition, the surface protective films of Examples 1 to 6 were free from contamination of the polarizing plate as a substrate and excellent in contamination resistance even after storage for 3 days and 30 days.

In other words, the evaluation results shown in Table 4 for the surface protective films of Examples 1 to 6 demonstrate that the problems of the present invention can be solved.

In the pressure-sensitive adhesive composition of Comparative Example 1, the weight average molecular weight of Copolymer B-5 was as low as 10,000. In addition, I-4 contained in the copolymer B-5 had a diester content of 0.8% and an average repeat number n of 23, which is large. The amount of the component (b) contained in the copolymer B-5 of the second acrylic polymer is 3 parts by weight and less than 5.5 parts by weight of the component (B) contained in the first acrylic polymer. The surface protective film of Comparative Example 1 using such a pressure-sensitive adhesive composition was excellent in stain resistance against polarizing plates based on TAC which had been conventionally used, but the staining resistance was somewhat poor for two types of polarizing plates based on PMMA or PET .

In the pressure-sensitive adhesive composition of Comparative Example 2, the mono (meth) acrylic acid ester monomer containing polyalkylene glycol chain was copolymerized with the first acrylic polymer, and the ratio of the copolymerizable monomer containing hydroxyl group (B) was as large as 6.5 parts by weight. The surface protective film of Comparative Example 2 using such a pressure-sensitive adhesive composition had a low adhesive force of 0.03 N / 25 mm at a low speed peeling rate of 0.3 m / min, poor adhesive performance, poor stain resistance to two types of polarizing plates , And the stain resistance of the other type of polarizing plate was somewhat poor.

Further, in the pressure-sensitive adhesive composition of Comparative Example 3, the proportion of the copolymerizable monomer (C) containing a carboxyl group was 1.5 parts by weight, and the antistatic agent contained anions of F5 having fluorine atom numbers of less than F7. The surface protective film of Comparative Example 3 using such a pressure-sensitive adhesive composition had a high peeling electrification voltage as high as 0.6 kV and had poor antistatic properties and also had poor stain resistance to three types of polarizing plates, It was rather poor.

As described above, the problems of the present invention were not solved in the surface protective films of Comparative Examples 1 to 3.

On the other hand, in the case of the surface protective film prepared in the same manner as in Example 1 except that the copolymer B was not contained, the surface resistivity was increased, the peeling electrification voltage was increased, the antistatic performance was poor, My pollution was also poor.

Claims (15)

A pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent and a crosslinking agent, wherein the acrylic polymer is a first acrylic polymer and a second acrylic polymer,
Wherein the first acrylic polymer comprises
(A) 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group having from 1 to 18 carbon atoms,
(B) 1.0 to 6.0 parts by weight in total of at least one copolymerizable monomer containing a hydroxyl group,
(C) 0.01 to 0.6 parts by weight of a total of at least one copolymerizable monomer containing a carboxyl group
(Meth) acrylate monomer containing no polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer and having an acid value of 0.1 to 1.0 and a weight average molecular weight of 300,000 to 1,200,000,
Wherein the first acrylic polymer contains 2-ethylhexyl acrylate in a proportion of 70 parts by weight or more among 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group of C1-C18 in the alkyl group Lt; / RTI &
Wherein the second acryl-based polymer comprises:
(a) at least one or more of (meth) acrylic acid ester monomers having an alkyl group having from 1 to 18 carbon atoms,
(b) at least one copolymerizable monomer containing a hydroxyl group, and
(c) at least one or more kinds of mono (meth) acrylic acid ester monomers containing polyalkylene glycol chain
A second acryl-based polymer of a copolymer obtained by copolymerization,
Wherein the glass transition temperature of the first acrylic polymer and the second acrylic polymer is 0 DEG C or lower,
Wherein the crosslinking agent is (D) an isocyanate compound having three or more functional groups,
Wherein the antistatic agent is (G) an ionic compound having a melting point of 25 to 50 캜 comprising a cation and an anion having an anion having a fluorine atom number of not less than F7,
Wherein the pressure-sensitive adhesive composition further comprises (E) a crosslinking retarder and (F) a crosslinking catalyst other than a tin compound as a crosslinking catalyst. The method according to claim 1,
Wherein the polarizer protective layer of the polarizing plate is one selected from the group consisting of a TAC-based film, a PMMA-based film and a PET-based film, and the polarizer protective layer of the polarizing plate Wherein the surface treatment performed on the surface of the layer is one selected from the group consisting of untreated, AG treated, LR treated, AR treated, AG-LR treated and AG-AR treated. 3. The method according to claim 1 or 2,
Wherein the anions of ionic compounds _{C 6 F 5 (CF 2)} n COO -, C 6 F 5 (CF 2) n SO 3 -, C 6 F 5 (CF 2) n O -, C 6 F 5 O ( ^{_{CF 2) n SO 3 -,}} (C 6 F 5 CO) 2 N -, (C 6 F 5 CO) 3 C -, (C 6 F 5 SO 2) 2 N -, (C 6 F 5 SO 2) ^{_{3 C -, (C 6 F}} 5 OSO 2) 2 N -, (C 6 F 5 OSO 2) 3 C -, (C 6 F 5) 4 B -, CF 3 (CF 2) 3 SO 3 - consisting of And at least one selected from the group consisting of anions,
Wherein the ionic compound is contained in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the first acrylic polymer. 3. The method according to claim 1 or 2,
Wherein the cation of the ionic compound is selected from the group consisting of pyridinium, imidazolium, phosphonium, sulfonium, pyrrolidinium, guanidinium, ammonium, isooronium, thiouronium, piperidinium, pyrazolium, And morpholinium,
Wherein the ionic compound is contained in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the first acrylic polymer. 3. The method according to claim 1 or 2,
Wherein the pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition has a surface resistivity of 1.0 x 10 ^{+ 12} ? /? Or less,
The peeling electrification voltage of the pressure-sensitive adhesive layer to the low-refractive index layer formed by using the composition for forming a low-refractive index layer containing a fluorine compound on the adhered surface is in the range of -0.3 to +0.0 kV,
Sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition with an adhesive force of 0.04 to 0.2 N / 25 mm at a low speed peeling rate of 0.3 m / min and an adhesive force of 2.0 N / 25 mm or less at a high peeling rate of 30 m / By weight. 3. The method according to claim 1 or 2,
Wherein the copolymerizable monomer containing the hydroxyl group of the first acrylic polymer and the copolymerizable monomer containing the hydroxyl group of the second acrylic polymer are selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, Hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, , N-hydroxyethyl (meth) acrylamide, and the like.
(Meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (Meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- Caprolactone mono (meth) acrylate, and 2- (meth) acryloyloxyethyltetrahydrophthalic acid. The pressure-sensitive adhesive composition according to claim 1, 3. The method according to claim 1 or 2,
Wherein the crosslinking retarder (E) is a keto-enol tautomer compound,
(E) a crosslinking retarder in an amount of 0.1 to 300 parts by weight based on 100 parts by weight of the first acrylic polymer,
The crosslinking catalyst (F) is at least one metal chelate compound selected from the group consisting of aluminum chelate compounds, titanium chelate compounds and iron chelate compounds,
(F) a crosslinking catalyst in an amount of 0.001 to 0.5 parts by weight based on 100 parts by weight of the first acrylic polymer,
Wherein the weight ratio of (E) / (F) is 80 to 1000. 3. The method according to claim 1 or 2,
Wherein the pressure-sensitive adhesive composition comprises 0.01 to 0.5 parts by weight of a polyether-modified siloxane compound having an HLB value of 6 to 12 and a weight-average molecular weight of 10,000 or less based on 100 parts by weight of the first acrylic polymer. . 3. The method according to claim 1 or 2,
Wherein the pressure-sensitive adhesive composition comprises the second acrylic polymer in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the first acrylic polymer,
Wherein the second acryl-based polymer comprises:
(a) 100 parts by weight of the total of at least one (meth) acrylate monomer having an alkyl group having from 1 to 18 carbon atoms,
(b) 2.0 to 12.0 parts by weight in total of at least one copolymerizable monomer containing a hydroxyl group,
(c) 1 to 30 parts by weight of a total of at least one kind of mono (meth) acrylic acid ester monomer containing a polyalkylene glycol chain
A copolymer having a weight average molecular weight of more than 300,000 and not more than 1,000,000,
(B) a total of at least one copolymerizable monomer containing a hydroxyl group (B) relative to 100 parts by weight in total of at least one (meth) acrylate monomer having an alkyl group of the C1-C18 alkyl group of the first acrylic polymer 100 parts by weight of at least one (meth) acrylate monomer having an alkyl group of C1 to C18 in the alkyl group (a) of the second acrylic polymer and a weight part (? 1 = 100 x (B) / (K =? 2 /? 1) of the total weight part (? 2 = 100 x (b) / (a)) of at least one copolymerizable monomer containing a hydroxyl group (b) is in the range of 1.0 to 2.0 . 3. The method according to claim 1 or 2,
Wherein the second acrylic polymer is a copolymer having a weight average molecular weight of 300,000 or more and 800,000 or less,
Wherein the polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer has an average number of repeating alkylene oxides constituting the polyalkylene glycol chain of 3 to 14,
The diester content in the mono (meth) acrylic acid ester monomer containing polyalkylene glycol chain is 0.2% or less,
(Meth) acrylate, methoxypolyalkylene glycol (meth) acrylate and ethoxypolyalkylene glycol (meth) acrylate as the polyalkylene glycol chain-containing mono (meth) acrylic acid ester monomer Based on 100 parts by weight of the second acrylic polymer, in an amount of 1 to 50 parts by weight based on 100 parts by weight of the second acrylic polymer. Wherein a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of claim 1 or 2 is laminated on one side of the resin film. A surface protective film using the adhesive film of claim 11. A surface protective film for a polarizing plate, wherein the pressure-sensitive adhesive film of claim 11 is used. An optical film comprising a pressure-sensitive adhesive layer formed by laminating a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of claim 1 or 2 on at least one surface of an optical film. 12. The method of claim 11,
Wherein an antistatic treatment and an antifouling treatment are performed on a side of the resin film one side opposite to the side where the pressure-sensitive adhesive layer is formed.